This invention is directed to a humidifier system, and in particular to a stationary evaporator tank having provision to be heated by a convector heater, using an external water supply.
Domestic humidification of the indoors during the heating season has received enormous attention in the past and has resulted in many varieties of moisture generators, with many and various ways of controlling the level of humidification achieved.
There are a number of problems involved in humidifying the air within a building, such as the presence of various salts and contaminants in solution in the feed water, and the concentration of dust and fluff around the heating means over a period of time, under the influence of convection air currents and associated air circulation.
One commonly used method to enhance the capacity of a system is the use of an evaporating wicking body, having air permeable, moisture wicking surfaces to achieve enhanced rates of evaporation as shown in U.S. Pat. Nos. 3,598,311 LAUFFENBURGER, issued Aug. 10, 1971 and 4,284,129 ROGALSKI, issued Aug. 18, 1981. A major disadvantage of such arrangements, particularly in "hard" water regions, is the precipitation and accumulation of the present salt materials out of solution onto the wicking surfaces, with consequent degradation, fouling and loss of effectiveness.
There has been a trend towards baseboard heating, both in individual homes and in apartment buildings having centralized heating plants. Such baseboard heating units generally comprise either hot water (or steam) circulation coils and electrical base board heaters. Most such heaters are characterized by their significant length, extending several feet along the base of a wall, hence the name; and possessing a low, narrow cross-sectional profile.
It is this characteristic profile which presents a number of difficulties that heretofore do not appear to have been overcome.
From an earlier age of water coil heaters that shared certain characteristics with present day hot water baseboard heaters, arrangements such as U.S. Pat. No. 1,601,810 ROGGE et al, issued Oct. 5, 1926 were provided, having an evaporator tank directly mounted on the coils, and being maintained at a predetermined water level by a reservoir tank located hereinabove. However, such an arrangement is unsuitable as a baseboard humidifier in that the structure of the evaporator and reservoir tanks constitute a major obstruction to upward conventional air circulation past the coils, with consequent loss in system effectiveness. Formerly, in ROGGE's times, this loss in effectiveness was compensated by over capacity of the radiators, which were generally large and bulky. These larger old-style radiators also transferred a significant portion of their output by radiation, hence their name. Furthermore, their operation was often continuous, in contrast to present-day heat-demand cycling.
One of the problems identified by the present inventors, for which a remedy has been provided, is the fact that heating by baseboard heaters generally is cyclic, which results in a short heat-up period, followed by an ensuing limited heating period, and an off-heat or "down" time in which energization of the heater unit, be it by hot water, steam, or electricity, is terminated.
Location of baseboard heaters is characteristically in the coldest locale of their environment, close to the floor and frequently below a window or other thermal discontinuity, in order to achieve maximum comfort, and effectiveness of function. Thus, during the off-heat periods, there is a significant cooling effect, such that the evaporator and its water content tend to be completely cooled off.
Thus, at the commencement of a heating cycle significant heat is required to bring the evaporator and its water content up to a vapour generating temperature.
In order to overcome the foregoing problems the present invention provides a humidifier system suitable for use with a baseboard type heater and posessing the following characteristics: wickless evaporation using a small, low profile section evaporator tank of relatively reduced length, permitting its selective location in a favourable location along the length of a baseboard heater. The low profile of the evaporator tank generally permits location of the evaporator tank directly on the fins of the baseboard heater, beneath the top grill of the heater. Furthermore the present invention provides an external reservoir, the system having a flow control to regulate the mass of water present in the evaporator and to limit its depth. This permits rapid warm-up and commencement of evaporation during the on-heat portion of a heating cycle. Furthermore, use of a flexible plastic feed pipe permits location of the reservoir in a concealed or other suitable access.
The system further provides in one preferred embodiment thereof a low mass, low specific heat, high conductivity evaporator tank, preferably of aluminum or an alloy thereof, to promote rapid warm-up to an effective temperature of vapourization.
The system further provides an evaporator tank having extended heat transfer areas, including air transfer passages to promote rapid warm-up and the substantially uninterrupted upward circulation of hot air in convectional heat transfer flow relation from a heated baseboard element therebeneath.
There is further provided means for selectively varying the depth of water within the evaporator tank, and adjustable tank cover means for selectively varying the output from the evaporator.